Share-Based Compensation - Stock Option Activity under Stock Option Plans (Details)	3 Months Ended
	Mar. 31, 2020 USD ($) $ / shares shares
Number of Shares
Beginning balance (in shares) | shares	59,350
Exercised (in shares) | shares	(1,050)
Ending balance (in shares) | shares	58,300
Vested and Expected to Vest (in shares) | shares	58,300
Exercisable (in shares) | shares	58,300
Weighted-Average Exercise Price
Beginning balance (in dollars per share) | $ / shares	$ 13.51
Exercised (in dollars per share) | $ / shares	6.71
Ending balance (in dollars per share) | $ / shares	13.63
Vested and Expected to Vest (in dollars per share) | $ / shares	13.63
Exercisable (in dollars per share) | $ / shares	$ 13.63
Weighted Average Remaining Contractual Term (in Years)
Outstanding (term)	2 years 2 months 23 days
Vested and Expected to Vest (term)	2 years 2 months 23 days
Exercisable (term)	2 years 2 months 23 days
Aggregate Intrinsic Value
Outstanding | $	$ 749,737
Vested and Expected to Vest | $	749,737
Exercisable | $	$ 749,737